[Gerrit]

Hello everyone,

I hope I am in the correct forum with my problem. I am simulating the heat transfer from a hot wire anemometer in a hydrogen stream with buoyantSimpleFoam. I am using polynomial functions for the fluid properties. My cases run and give results that make sense so far.
Now as I was about to finish the project I wanted to check everything again and found a fundamental problem with my cases:

To gain the heat transfered from the wire to the fluid I used "wallHeatFlux" and it gave logical results so far. Now I made a short calculation, first law of thermodynamics, relating inlet and outlet enthalpies with the mass flow and got a heat flow which is approx 1.7 times smaller than with "wallHeatFlux".

I gained the temperature at the outlet with "patchAverage T outlet" and the heat capacities with my polynomial functions.

I checked everything five times and do not know where this crude difference might come from. The biggest problem is, that I do not know which result I should trust.

Furthermore it becomes more confusing, as I have other simulations where only the velocity and the fluid properties where changed. These do not have this problem - there I get nearly the same heat flows with the described ways.

I hope it is possible to understand my problem so far.

Does someone have an idea?

Thank you very much!

Best regards